I got a problem with borders in swing and Java 8 (tried both the 5 and 11 update) on Windows 8.1 Update 1 x64.
The western border has 1px more thickness than the others. So if I set the border to 1px the left border has 2px. See the attached picture...

Tried BorderFactory and Border-Objects... When I set a custom border the problem occurs. The built in borders work fine.